Pictures for vision: how can they identify the problem with their help?

Ignore periodic checks of the health of the eyes is wrong, even if there is no noticeable cause for excitement.Sudden vision impairment associated with trauma or illness is hard to notice. But gradually accumulating problems, gradually "undermining" the quality of the work of the organs of vision, can be practically imperceptible. The obvious signs of the accumulated disorder of the visual apparatus are often similar to fatigue or temporary circumstances.

This attitude can be a serious mistake.Among the eye ailments there are many such that develop asymptomatically. That is why it is important to conduct a comprehensive and accurate assessment of the state of vision without waiting for irreversible changes. This is possible at the present time, since modern diagnostics equipment and qualitative methods are used in the survey.

Why check

The vision test includes the determination of visual field defects, the ability to distinguish colors, the status of the fundus. But first of all, at the examination, visual acuity is checked. This is one of the main functions of the eye. Deterioration of visual acuity occurs for a number of reasons: eye diseases, neurological problems, refractive errors, or trauma. The very concept of "visual acuity" means the ability of the human eye to see two different luminous points from each other at the smallest angle of view. The value of the angle is measured in minutes. Normal vision is considered, in which the angle of view is one minute. Such an indicator of visual acuity is taken as one.

Verification of visual acuity is not the only method of examination available to modern ophthalmology. But it is fast enough and informative. According to the results, the doctor can determine whether further examinations are necessary.

The goal that the ophthalmologist and patient set for themselves is the timely identification of the potential danger of a disorder in the organs of vision.It is important to determine as early as possible how much treatment, vision correction is needed at this time.Sometimes the most correct is the observation of the dynamics of the development of processes occurring in the eye. Obligatory checking of eyesight before assigning those or other methods of correction: corrective glasses or contact lenses.

Corrective glasses

Sometimes a visual quality examination is carried out in cases where it is necessary to certain types of work, for obtaining a driver's license, at a military registration and enlistment office or with other important circumstances.A visual examination is absolutely necessary in the following cases:

1. People who do not feel any problems with visual perception. In this case, preventive testing can be done no more than once a year;
2. When a patient feels uncomfortable with visual perception.If a person's vision falls, the doctor will be able to guess the cause of the impairment as a result of the examination and recommend a correction method. The importance of this examination is also in the fact that some ophthalmic diseases, similar in symptoms to hyperopia or nearsightedness;
3. If the correction of vision is carried out with the help of contact lenses.The need for checks is explained by the ability of the lens (foreign body) to cause subtle changes in the eye;
4. If a pregnancy is planned.The doctor will be able to determine whether it is necessary to carry out pre-birth retina reinforcement with barrier laser coagulation;
5. To older people (after 40-50 years). This will help to identify at an early stage the risk of such age-related eye diseases as cataracts or glaucoma;
6. Children.The visual analyzer at an early age continues to evolve and form. Examination of the child's vision is necessary in time to detect and as soon as possible to correct the problems that arise.

Cataract

Ignore the examination is not necessary for people suffering from nervous and cardiovascular pathologies that have a reduced blood pressure, those who suffered an eye injury, patients who undergo long-term hormonal treatment preparations.

Existing tables for verification

Verification of visual acuity is indicated by the term "visometry".Its principle is based on the recognition of objects, which are called optotypes. The principles of constructing even different optotypes are practically the same: the ratio of the width of the entire object to the element from which it is constructed is equal to:. The study of visual acuity is carried out by demonstrating to the patient tables, consisting of special symbols of various sizes. During the examination, the patient is invited to recognize and name those or other symbols.

Determination of visual acuity (visometry)

Visual acuity is checked first for each eye separately. The patient is then asked to look at the cutoff table with two eyes simultaneously. If a person wears glasses, then at this stage corrective lenses are used.

There are several types of tables that use optotypes to test visual acuity.

The Sitseva table

Sivtsev's table is twelve rows of Cyrillic letters, which are optotypes. The largest optotypes are located on the first line.Their dimensions are such that, under normal vision, they can be distinguished without tension from a distance of 50 meters. Further, the distance between the elements of the signs (bars and dashes, from which letters consist) is proportionally reduced. The signs of the tenth line with normal vision are clearly distinguishable from a distance of five meters.

The visual acuity in the study by this method is described as a fraction. Normal vision is designated as 10/10, or,. In the event that at a distance of five meters a person can determine only the first line, his vision will be indicated as 1/10, or,. All values ​​are indicated on the table to the left of the optotypes.

Sivtsev's table

In the table there are 11th and 12th lines. To test visual acuity, they are used very rarely: only in those cases when a person is able to clearly see the signs beyond the tenth line. It is extremely important for such people to check the visual acuity on both eyes.

The Snellen table

People using the Latin alphabet for reading, to check the visual acuity offer a table Snellen.This method was developed back in the 19th century and is the prototype of the Sivtsev table. The Snellen table is almost the same as the Sivtsev table. However, there is a fundamental difference between them. The maximum possible distance for perception does not coincide. The first line is read not from 50, but from 60 meters. Accordingly, the following distances should be a multiple of six. The Snellen table consists of eleven lines.

The Snellen table

Indicator 6/6 is considered the norm. It is necessary to see one of the last lines from a distance of 6 meters.

Orlova's Table

Orlova's table is constructed according to the same principle as the Sittsev table. However, instead of letters in the survey, optotypes are used in the form of pictures (fly agaric, star, teapot). Theoretically, the Orlova table study can be used for any patient.However, in most cases, this method is used when working with children of preschool and primary school age (if the child can not read).

Orlova's Table

Golovin's Table

The Golovin table is also similar to the Sivtsev table. The difference is that, as optotypes, it uses figures that are called Landolt rings.These are really rings in which there are idiosyncratic "gaps".The gaps in each of the rings are arranged differently: bottom, top, right or left. In each ring, "gaps" are equal in width and height. The patient needs to determine in which direction the "rupture" is directed.

Golovin's Table

Such a table is used when the patient, as a result of many checks, has already learned the arrangement of letters on other tables and more guesses about the value of the optotype than sees it.

In many cases, this table is used as an additional table for diagnosis using the Sivtsev table.

Which tables are checked for drivers' vision

To assess the visual acuity needed to obtain a document that allows driving, doctors use the tables of Sivtsev and Golovin.It is important to determine the "quality of work" of a stronger and weaker eye. In those cases where visual acuity is insufficient, the patient is offered vision correction with the help of contact lenses, glasses, or with the help of surgical intervention.

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conclusions

The World Health Organization publishes data on the fact that on Earth more than 285 million people have vision problems.In most cases, pathological processes could be prevented.This requires timely diagnosis, regular preventive provarkov quality work of the visual apparatus. Now this is all the more urgent since in the modern world the burden on the eyes is increasing. In the workflow, and the very life of many people, the computer has firmly entered.

Another "sign" of our time was an allergy. Its manifestations can also be complicated by temporary or permanent impairment of vision.Eye diseases are a problem not only for older people. Hyperopia, strabismus, myopia, amblyopia, retinal damage and many other ailments affect vision in childhood.Timely detection of the problem will also save the children from aggravation of the pathological condition. A vision test is a procedure that is necessary for any modern person. Tables are one of the methods of research, proven and reliable.